U.S. patent application number 12/878421 was filed with the patent office on 2011-03-31 for video projector.
This patent application is currently assigned to SANYO ELECTRIC CO., LTD.. Invention is credited to Nobuyuki Kondou, Ken Mashitani, Shinya Noda.
Application Number | 20110075111 12/878421 |
Document ID | / |
Family ID | 43780012 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110075111 |
Kind Code |
A1 |
Noda; Shinya ; et
al. |
March 31, 2011 |
VIDEO PROJECTOR
Abstract
A video projector including a cooling current discharging
structure capable of providing a high-speed cooling current and a
low-speed cooling current to an optical component of an optical
system serving as a cooling subject. The cooling current
discharging structure discharges the high-speed cooling current
toward a high-temperature region of the optical component and
discharges the low-speed cooling current toward a low-temperature
region having a relatively low temperature.
Inventors: |
Noda; Shinya; (Daito-shi,
JP) ; Kondou; Nobuyuki; (Moriguchi-shi, JP) ;
Mashitani; Ken; (Neyagawa-shi, JP) |
Assignee: |
SANYO ELECTRIC CO., LTD.
Osaka
JP
|
Family ID: |
43780012 |
Appl. No.: |
12/878421 |
Filed: |
September 9, 2010 |
Current U.S.
Class: |
353/58 ; 348/744;
348/E9.025; 353/61 |
Current CPC
Class: |
H04N 9/3144
20130101 |
Class at
Publication: |
353/58 ; 348/744;
353/61; 348/E09.025 |
International
Class: |
H04N 9/31 20060101
H04N009/31 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2009 |
JP |
2009-226252 |
Claims
1. A video projector comprising: an optical system including an
optical component; and a cooling current discharging structure
capable of providing a high-speed cooling current and a low-speed
cooling current to the optical component of the optical system, the
optical component serving as a cooling subject, wherein the cooling
current discharging structure discharges the high-speed cooling
current toward a high-temperature region of the optical component
and discharges the low-speed cooling current toward a
low-temperature region having a relatively low temperature.
2. The video projector according to claim 1, wherein the cooling
current discharging structure includes a high-speed air passage
having a nozzle that discharges the high-speed cooling current.
3. The video projector according to claim 1, wherein the cooling
current discharging structure further includes a low-speed air
passage that discharges the low-speed cooling current and surrounds
the nozzle of the high-speed air passage to form a double duct.
4. The video projector according to claim 2, wherein the cooling
current discharging structure includes a blower port that
discharges the low-speed cooling current, and the nozzle that
discharges the high-speed cooling current is located in the blower
port so as to be surrounded by the discharged low-speed cooling
current.
5. The video projector according to claim 4, wherein the cooling
current discharging structure includes a low-speed air passage
having the blower port that discharges the low-speed cooling
current; the blower port is formed at a distal end of the low-speed
air passage; the nozzle is formed at a distal end of the high-speed
air passage; and the low-speed air passage and the high-speed air
passage form a double duct located at least ahead of the blower
port.
6. The video projector according to claim 5, wherein the low-speed
air passage includes: a first blower; a first blower duct connected
to the first blower; and a blower chamber connected to the first
blower duct and located ahead of the blower port; and the
high-speed air passage includes: a second blower; a second blower
duct connected to the second blower; and an inner duct connected to
the second blower duct, inserted in the blower chamber, and
supported by the blower chamber.
7. The video projector according to claim 6, wherein the first
blower duct in the low-speed air passage is connected to a side
wall of the blower chamber; and the inner duct in the high-speed
air passage includes a side surface having a horizontal
cross-section tapered toward a flow of air drawn in from the first
blower duct.
8. The video projector according to claim 7, wherein the blower
port discharging the low-speed cooling current is defined by an
upright wall formed by bending an upper end of the blower chamber
inward and upward, and the blower part has an opening area that is
smaller than a cross-sectional area of the blower chamber.
9. The video projector according to claim 3, wherein the high-speed
air passage includes a first engaging portion arranged near the
nozzle, and the low-speed air passage includes a second engaging
portion engaged with the first engaging portion.
10. The video projector according to claim 1, wherein the first
blower and the second blower are different types of blowers, and
the second blower is a blower more suitable for generating
high-pressure air current than the first blower.
11. A video projector comprising: an optical system including an
optical component; and a cooling current discharging structure that
provides first and second airflow cooling currents to the optical
component of the optical system in which one of the airflow cooling
currents has a higher flow speed than the other of the airflow
cooling currents, the optical component serving as a cooling
subject, wherein the cooling current discharging structure
discharges the one of the airflow cooling currents having a higher
flow speed toward a first region of the optical component and
discharges the other of the airflow cooling currents toward a
second region of the optical component in which the first region
when the optical system is operating has a higher temperature than
the second region.
12. The video projector according to claim 11, wherein the cooling
current discharging structure includes a high-speed air passage
having a nozzle that discharges the one of the airflow cooling
currents having a higher flow speed.
13. The video projector according to claim 11, wherein the cooling
current discharging structure further includes a low-speed air
passage that discharges the other of the airflow cooling currents
and surrounds the nozzle of the high-speed air passage to form a
double duct.
14. The video projector according to claim 12, wherein the cooling
current discharging structure includes a blower port that
discharges the other of the airflow cooling currents, and the
nozzle that discharges the one of the airflow cooling currents
having a higher flow speed is located in the blower port so as to
be surrounded by the discharged other of the airflow cooling
currents.
15. The video projector according to claim 14, wherein the cooling
current discharging structure includes a low-speed air passage
having the blower port that discharges the other of the airflow
cooling currents; the blower port is formed at a distal end of the
low-speed air passage; the nozzle is formed at a distal end of the
high-speed air passage; and the low-speed air passage and the
high-speed air passage form a double duct located at least ahead of
the blower port.
16. The video projector according to claim 15, wherein the
low-speed air passage includes: a first blower; a first blower duct
connected to the first blower; and a blower chamber connected to
the first blower duct and located ahead of the blower port; and the
high-speed air passage includes: a second blower; a second blower
duct connected to the second blower; and an inner duct connected to
the second blower duct, inserted in the blower chamber, and
supported by the blower chamber.
17. The video projector according to claim 16, wherein the first
blower duct in the low-speed air passage is connected to a side
wall of the blower chamber; and the inner duct in the high-speed
air passage includes a side surface having a horizontal
cross-section tapered toward a flow of air drawn in from the first
blower duct.
18. The video projector according to claim 17, wherein the blower
port discharging the other of the airflow cooling currents is
defined by an upright wall formed by bending an upper end of the
blower chamber inward and upward, and the blower part has an
opening area that is smaller than a cross-sectional area of the
blower chamber.
19. The video projector according to claim 13, wherein the
high-speed air passage includes a first engaging portion arranged
near the nozzle, and the low-speed air passage includes a second
engaging portion engaged with the first engaging portion.
20. The video projector according to claim 11, wherein the first
blower and the second blower are different types of blowers, and
the second blower generates a higher pressure air current than the
first blower.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2009-226252,
filed on Sep. 30, 2009, the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a video projector, and more
particularly to a video projector that cools an optical component
with a cooling current.
[0003] In the prior art, a video projector includes optical systems
that are arranged in a housing. The optical systems include an
illumination optical system having a light source or the like, a
splitting optical system that splits illumination light into a red
light, green light, and blue light, light valves modulating the
colored lights in accordance with video information, a combining
optical system that combines the modulated lights, and a projector
lens enlarging and projecting the combined light. Due to the
increased illuminance of images, recent projectors use light
sources that emit a large amount of light. Further, recent
projectors have become more compact. This has resulted in a
tendency for heat to build up inside the projectors. It is thus
important for optical components vulnerable to heat to be cooled,
such as an emission side polarizing plate of a light valve and a
polarizing beam splitter (PBS) of the illumination optical
system.
[0004] These optical components are generally cooled by delivering
a flow of air from a blower to a subject to be cooled (cooling
subject) through a duct and supplying a predetermined amount of air
to a predetermined location with a deflection plate and a nozzle.
Japanese Laid Open Patent Publication Nos. 2007-298890 and
2000-81667 describe prior art examples of such a cooling
scheme.
[0005] In the prior art cooling scheme described above, the amount
of air and blowing location of a nozzle are selected in accordance
with the cooled optical component. This is because the optical
components that are cooled have different temperature rising rates
and different tolerable temperature limits. However, in an optical
component that is vulnerable to heat such as those described above,
the temperature does not rise evenly in the entire optical
component. Thus, the temperature distribution is not uniform. More
specifically, as shown in FIG. 1, there is a tendency for the
temperature to be higher at a central portion in which a large
amount of light is concentrated, and there is a tendency for the
temperature to be lower as a peripheral portion becomes closer.
However, in the prior art cooling scheme, the blower cools such an
optical component entirely by blowing air against the optical
component. Such a cooling scheme does not take into consideration
the temperature distribution of the cooled optical component. Since
a temperature rise in part of an optical component would be dealt
with by increasing the entire amount of air, when a projector uses
a light source emitting an increased amount of light and has a
smaller size, the amount of air would be significantly increased.
This would lower efficiency and increase noise.
SUMMARY OF THE INVENTION
[0006] The present invention provides a video projector that
efficiently cools an optical component, while taking into
consideration the temperature distribution of the optical
component.
[0007] One aspect of the present invention is a video projector
provided with an optical system, which includes an optical
component, and a cooling current discharging structure, which is
capable of providing a high-speed cooling current and a low-speed
cooling current to the optical component of the optical system. The
optical component serves as a cooling subject. The cooling current
discharging structure discharges the high-speed cooling current
toward a high-temperature region of the optical component and
discharges the low-speed cooling current toward a low-temperature
region having a relatively low temperature.
[0008] A further aspect of the present invention is a video
projector provided with an optical system, which includes an
optical component, and a cooling current discharging structure,
which provides first and second airflow cooling currents to the
optical component of the optical system in which one of the airflow
cooling currents has a higher flow speed than the other of the
airflow cooling currents. The optical component serves as a cooling
subject. The cooling current discharging structure discharges the
one of the airflow cooling currents having a higher flow speed
toward a first region of the optical component and discharges the
other of the airflow cooling currents toward a second region of the
optical component in which the first region when the optical system
is operating has a higher temperature than the second region.
[0009] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention is illustrated by way of example and
is not limited by the accompanying figures, in which like
references indicate similar elements. Elements in the figures are
illustrated for simplicity and clarity and have not necessarily
been drawn to scale. In the drawings, like numerals are used for
like elements throughout:
[0011] FIG. 1 is a chart showing the general temperature
distribution in an optical component;
[0012] FIG. 2 is a schematic view showing optical systems of a
representative video projector according to one embodiment of the
present invention;
[0013] FIG. 3 is a plan view showing a light valve for a red light
and its surroundings in the video projector of FIG. 1.
[0014] FIG. 4 is a cross-sectional view taken along line A-A in
FIG. 3;
[0015] FIG. 5 is a cross-sectional view taken along line B-B in
[0016] FIG. 3;
[0017] FIG. 6 is a cross-sectional view of a blower chamber for a
low-speed air passage in a modification of the video projector;
[0018] FIG. 7 is a cross-sectional plan view of a high-speed air
passage in a modification of the video projector; and
[0019] FIG. 8 is a perspective view showing an engaging portion
formed at a distal portion of the high-speed air passage in a
modification of the video projector.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Optical systems in a video projector according to the
present invention will first be described with reference to FIG.
2.
[0021] The video projector is a liquid crystal display (LCD) video
projector and is of a three-panel type in this example. Optical
systems of the projector include an illumination optical system 10,
which emits illumination light, and a color splitting optical
system 20, which splits the illumination light emitted from the
illumination optical system 10 into a red light, green light, and
blue light. The optical systems further include a red light valve
30, a green light valve 40, and a blue light valve 50 respectively
modulating the red light, green light, and blue light split by the
color splitting optical system 20. The optical systems also include
a color combining optical system 60, which combines the modulation
lights modulated by the light valves 30, 40, and 50, and a
projection optical system 70, which enlarges and projects the
combined light emitted from the color combining optical system 60
as a colored image light onto a screen or the like.
[0022] The illumination optical system 10 includes a light source
lamp 11, an integrator lens 12, a polarizing beam splitter 13, a
condenser lens 14, a reflection mirror 15, and a relay lens 16. A
light beam is emitted from the light source lamp 11 toward the
integrator lens 12, which includes a first lens array arranged at
an entry side and a second lens array arranged at an emission side.
A plurality of cell lenses in the first lens array divides the
light beam emitted to the integrator lens 12 into a plurality of
fine partial light beams. Then, each of the partial light beams
emitted from the first lens array is converged on a corresponding
cell lens in the second lens array. Further, the polarizing beam
splitter 13 gathers the light beams emitted from the integrator
lens 12 and forms predetermined polarized light, which is emitted
via the condenser lens 14, reflection mirror 15, and relay lens 16
to the color splitting optical system 20.
[0023] The color splitting optical system 20 includes dichroic
mirrors 21 and 22, reflection mirrors 23, 24, and 25, relay lenses
26 and 27, condenser lenses 28r, 28g, and 28b and function to split
the illumination light emitted from the illumination optical system
10 into a red light, a green light, and a blue light.
[0024] The first dichroic mirror 21 transmits red light and
reflects green light and blue light. The red light transmitted
through the first dichroic mirror 21 is reflected by the reflection
mirror 23 and transmitted through the condenser lens 28r to
illuminate the red light valve 30. The condenser lens 28r converges
the partial light beams from the illumination optical system 10 at
the red light valve 30 to form a light beam in which the partial
light beams are substantially parallel to one another. The
condenser lenses 28g and 28b respectively arranged at the entry
sides of the green light valve 40 and the blue light valve 50 are
formed in a manner similar to the condenser lens 28r.
[0025] Among the green light and blue light reflected by the first
dichroic mirror 21, the green light is reflected by the second
dichroic mirror 22 and transmitted through the condenser lens 28g
to illuminate the green light valve 40. In contrast, the blue light
is transmitted through the second dichroic mirror 22 and
sequentially travels to the relay lens 26, the reflection mirror
24, the relay lens 27, the reflection mirror 25, and the condenser
lens 28b to illuminate the blue light valve 50.
[0026] The red light valve 30 includes an entry side polarizing
plate 31 arranged at the entry side, an optical compensation plate
32, a transmissive liquid crystal panel 33, a pre-polarizing plate
34, and an emission side polarizing plate 35 in a manner similar to
the structure of the prior art. The green light valve 40 includes
an entry side polarizing plate 41 arranged on the entry side, an
optical compensation plate 42, a transmissive liquid crystal panel
43, a pre-polarizing plate 44, and an emission side polarizing
plate 45 arranged on the emission side. The blue light valve 50
includes an entry side polarizing plate 51 arranged on the entry
side, an optical compensation plate 52, a transmissive liquid
crystal panel 53, a pre-polarizing plate 54, and an emission side
polarizing plate 55 arranged on the emission side.
[0027] The color combining optical system 60 includes a cross
dichroic prism 61. The cross dichroic prism 61 has a reflection
surface 61a, which reflects the red light modulated by and emitted
from the red light valve 30, and a reflection surface 61b, which
reflects the blue light modulated by and emitted from the blue
light valve 50. The red and blue lights, which enter the cross
dichroic prism 61 and are reflected by the reflection surfaces 61a
and 61b, are combined with the green light, which enters and
transmits straight through the cross dichroic prism 61. The
combined light is emitted from the cross dichroic prism 61 as a
colored image.
[0028] The projection optical system 70 is arranged at the emission
side of the cross dichroic prism 61 and includes a projector lens
unit.
[0029] In such optical systems, the light source increases the
temperature. Further, the polarizing beam splitter 13 and the light
valves 30, 40, and 50 are formed by optical components having a
relatively low tolerable temperature limits. In this case, the
temperature increases is highest at the emission side polarizing
plates 35, 45, and 55, which regulate the amount of emitted light.
Further, the central portion of each of these optical components
receives a larger amount of light from the light source. Thus,
there is a tendency for the temperature to be higher at the central
portion and lower as the peripheral portion becomes lower as shown
in FIG. 1.
[0030] A cooling structure for optical components according to the
present invention will now be discussed with reference to FIGS. 3
to 5. Here, the red light valve 30 will be used as an example for
describing the cooling structure. FIG. 3 is a plan view. In the
following description, the vertical direction refers to a direction
perpendicular to the plane of FIG. 3, with the upper side of FIG. 3
being defined as the upper side.
[0031] FIG. 3 is a schematic plan view showing the cooling
structure for cooling the optical components of the red light valve
30 with a cooling current. As viewed in the drawing, a double duct
type air conduit is formed below the optical components of the red
light valve 30. More specifically, the air conduit includes an
outer air passage and an inner air passage. The outer air passage
is a low-speed air passage 80 through which air flows at a low
speed, and the inner air passage is a high-speed air passage 90
through which air flows at a high speed.
[0032] The low-speed air passage 80 includes a blower 81, a blower
duct 82 connected to the outlet side of the blower 81, a blower
port 83 that discharges a cooling current toward the optical
components of the red light valve 30 from below (refer to FIG. 4),
and a blower chamber 84 formed ahead of the blower port 83.
[0033] A normal low pressure fan, such as a sirocco fan, of which
the specifications are suitable for discharging an air current from
the blower port 83 at a low speed, is used as the blower 81. The
blower duct 82 provides a cooling current airway to the blower
chamber 84 through a side wall thereof. In the present embodiment,
the blower port 83 is formed with a shape that opens upwardly from
the blower chamber 84. The dimension of the blower port 83 in the
lateral direction of FIG. 3 (direction perpendicular to the light
axis) is set to be slightly greater than the lateral dimensions of
the optical components (light valve 30 in this case). The dimension
of the blower port 83 in the light axis direction is set to be
large enough to include the entry side polarizing plate 31 to the
emission side polarizing plate 35 (refer to FIG. 4). In this
manner, the blower port 83 is formed so as to discharge a
predetermined amount of cooling current airflow at predetermined
speed over the entire range of optical components in the light
valve 30 excluding the portion in which a high-speed cooling
current is discharged from a nozzle 94 of the high-speed air
passage 90. The cooling current discharged from the blower port 83
is slower than the cooling current discharged from the nozzle 94.
Thus, in this specification, the cooling current discharged from
the blower port 83 is referred to as a low-speed current, and the
cooling current discharged from the nozzle 94 is referred to as a
high-speed current.
[0034] The high-speed air passage 90 includes a blower 91, a blower
duct 92 connected to the outlet side of the blower 91, an inner
duct 93 inserted inside the blower chamber 84, and a nozzle 94
formed at the distal portion of the high-speed air passage 90, that
is, at the distal portion of the inner duct 93 in the present
embodiment.
[0035] A high pressure fan, such as a turbo fan, of which the
specifications are suitable for discharging an air current from the
nozzle 94 at a high speed, is used as the blower 91. The blower
duct 92 extends upward from the lower surface of the blower chamber
84. The inner duct 93, which is a duct portion arranged in the
blower chamber 84, is supported in the blower chamber 84 by a
portion connected to the blower duct 92. The inner duct 93 includes
a side surface 93a formed to have a horizontal cross-section that
is tapered (triangular in the present embodiment) toward the air
current flowing from the sideward blower duct 82 (refer to FIGS. 3
and 5). The side surface 93a allows for the air current drawn in
from the blower duct 82 to flow smoothly to the rear of the inner
duct 93, that is, to the right as viewed in FIG. 3.
[0036] As shown in FIG. 3, the nozzle 94 is arranged to cool the
central portions of the pre-polarizing plate 34 and the emission
side polarizing plate 35, which are located at the light emission
side where there is a tendency for the temperature to easily
increase. As apparent from FIG. 3, the nozzle 94 is formed with a
dimension that covers the liquid crystal panel 33, the
pre-polarizing plate 34, and the emission side polarizing plate 35
of the red light valve 30 in the light axis direction. Further, in
the lateral direction perpendicular to the light axis, the size and
location of the nozzle 94 are set to discharge a high-speed cooling
current at predetermined speed to the central portion of the
optical component (light valve 30). Further, as shown in FIGS. 4
and 5, the nozzle 94 has tapered portions 94a that are sloped so
that its dimensions become smaller as the distal end (i.e., top
end) becomes closer.
[0037] The structure for strongly cooling the central portions of
the pre-polarizing plate 34 and the emission side polarizing plate
35 has been described above. In the video projector according to
the present embodiment, the pre-polarizing plate 44 and emission
side polarizing plate 45 in the green light valve 40 and the
pre-polarizing plate 54 and emission side polarizing plate 55 in
the blue light valve 50 are also cooled in the same manner.
[0038] In the video projector, the optical components are cooled as
described below.
[0039] Some of the optical components in the optical systems are
vulnerable to heat, for example, the entry side polarizing plates
31, 41, and 51, the optical compensation plates 32, 42, and 52, the
liquid crystal panels 33, 43, and 53, the pre-polarizing plates 34,
44, and 54, and the emission side polarizing plates 35, 45, and 55
of the light valves 30, 40, and 50. The polarizing beam splitter 13
is also vulnerable to heat. Further, the temperature distribution
is not uniform in such optical components as shown in FIG. 1, and
the temperature has a tendency of being higher at the central
portions of such optical components in surfaces perpendicular to
the light axis. That is, in each of such optical components, the
central portion forms a high-temperature region, and the peripheral
portion forms a low-temperature region having relatively low
temperature. Among these optical components, the rise in
temperature is highest in the pre-polarizing plates 34, 44, and 54
and the emission side polarizing plates 35, 45, and 55. In the
present embodiment, in order to strongly cool the high-temperature
region in the central portion of each of these optical components
especially at the emission side, cooling current is discharged at a
high speed from the nozzle 94 by the high-speed, high-pressure
blower 91. This lowers the temperature of the high-temperature
regions in these optical components and decreases temperature
variations. Further, the low-temperature region surrounding the
high-temperature region, that is, the peripheral portion of each
optical component, is cooled by discharging air from the normal
blower 81. The peripheral portion of the optical component is also
cooled by a swirling air current generated by the speed difference
between the air currents. In this manner, cooling currents of two
or more speeds are used. This efficiently cools the optical
components. Further, such a structure decreases temperature
variations in the optical component and allows for a uniform
temperature distribution.
[0040] The video projector according to the present embodiment has
the advantages described below.
[0041] (1) The video projector includes a cooling current discharge
structure that discharges high-speed cooling current to the
high-temperature region of an optical component and discharges a
low-speed cooling current to the low-temperature region at which
the temperature is relatively low. By using such a finely regulated
cooling means, cooling is performed without using unnecessary
amounts of air and unnecessary current speeds. This improves the
cooling effect and efficiency, while reducing noise. Further,
temperature variations are decreased in the optical components and
the cooling capacity is increased. Thus, the reliability and
durability of the optical components are improved.
[0042] (2) The nozzle 94 that discharges the cooling current is
formed at the distal end of the high-speed air passage 90. This
efficiently discharges cooling current to the high-temperature
regions of the optical components and thereby increases the cooling
capacity.
[0043] (3) The nozzle 94, which discharges the high-speed cooling
current, is located inside the blower port 83, which discharges the
low-speed cooling current. Further, the periphery of the nozzle 94
is surrounded by the low-speed cooling current. Accordingly, a
cooling current optimal for the temperature distribution of the
cooled optical component is discharged from the nozzle 94. Further,
the cooling current directed to the peripheral portion of the
optical component draws in surrounding air due to the pressure
difference corresponding to the current speed difference. This
reduces the amount of air used to cool the peripheral portion and
further improves efficiency.
[0044] (4) The nozzle 94 formed at the distal end of the high-speed
air passage 90 is arranged in the blower port 83 formed at the
distal end of the low-speed air passage 80. Accordingly, the
high-speed air passage 90 and the low-speed air passage 80 form a
double duct at least at a location just ahead of the blower port
83. This simplifies the structures for a cooling current passage
for a cooling subject.
[0045] (5) The blower chamber 84 is provided ahead of the blower
port 83 in the low-speed air passage 80, and the blower duct 92
connected to the blower 91 in the high-speed air passage 90 is
inserted in the blower chamber 84. This forms a double duct.
Accordingly, the inner duct 93 in the high-speed air passage 90 is
supported by the low-speed air passage 80. This facilitates the
mounting of the high-speed air passage 90.
[0046] (6) The blower duct 82 in the low-speed air passage 80 is
connected to the side wall of the blower chamber 84, and the
high-speed air passage 90 includes the side surface 93a, which has
a horizontal cross-section tapered toward the air current from the
blower duct 82. Accordingly, the flow of air drawn from the blower
duct 82 into the low-speed air passage 80 is smoothly guided to the
rear of the high-speed air passage (inner duct 93), that is, toward
the right as viewed in FIG. 3. This forms a uniform low-speed air
current around the high-speed air passage 90.
[0047] (7) The blower 91 for generating the high-speed cooling
current and the blower 81 for generating the low-speed cooling
current are different types of blowers, and the blower 91 is more
suitable for generating high-pressure air current than the blower
81. Accordingly, air currents are generated at speeds optimal for
their applications (i.e., temperature regions).
[0048] It should be apparent to those skilled in the art that the
present invention may be embodied in many other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the present invention
may be embodied in the following forms.
[0049] The cooling structure of the above-discussed embodiment
cools the pre-polarizing plates 34, 44, and 54 and the emission
side polarizing plates 35, 45, and 55 with cooling currents of two
speeds. In the same manner, any component having a temperature
distribution variation such as the other optical components in the
light valves 30, 40, and 50, the polarizing beam splitter 13, and
the light source may also be cooled by cooling currents of two
speeds.
[0050] As shown in FIG. 6, the blower port 83 discharging the
low-speed cooling current may have an opening area that is smaller
than the cross-sectional area of the blower chamber 84. More
specifically, the upper end of the blower chamber 84 may be bent
inward and then upward to form an upright wall 84b that defines the
blower port 83. In this structure, the blower port 83 is narrower
than the blower chamber 84. This moderates the effect of dynamic
pressure produced by the air current drawn into the blower duct 82
and uniformly distributes the speed of the air current discharged
from the blower port 83. Further, the upright wall 84b may function
as a deflection plate.
[0051] The side surface 93a of the inner duct 93 located at the
outlet side of the blower duct 82 is not required to have a tapered
triangular shape and may be, for example, semicircular in shape
(refer to FIG. 7) or semielliptical. Such forms would also allow
for air to smoothly flow from the low-speed air passage 80 toward
the rear of the inner duct 93 (toward the right in FIG. 3).
[0052] An engaging portion for positioning the high-speed air
passage 90 relative to the low-speed air passage 80 may be arranged
at the distal portion of the high-speed air passage 90, which
includes the nozzle 94. In this case, in addition to fixing the
inner duct 93 to an insertion portion 84a, but the nozzle 94 may be
positioned with further accuracy. This accurately discharges
cooling current to the region subject to cooling. FIG. 8 shows an
example of an engaging portion. Arms 95 extend from near the nozzle
94 toward the top end of the blower chamber 84. Each arm 95 has a
distal portion forming an engaging portion 95a, which is rod-shaped
and curved and thereby has a circular cross-section. The blower
chamber 84 includes supports 85, each having an engaging portion
85a formed by a hole for insertion of the corresponding engaging
portion 95a. Accordingly, insertion of the rod-shaped curved
engaging portions 95a into the holes of the engaging portions 85a
stabilizes the position and direction of the nozzle 94 and
accurately adjusts the direction of the cooling current.
[0053] In the above-discussed embodiment, as apparent from FIG. 3,
the low-speed air passage 80 is formed so that the blower duct 82
has a cross-sectional area smaller than that of the blower chamber
84 the low-speed air passage 80. However, the low-speed air passage
80 is not limited to such a structure, and the cross-sectional area
of the blower duct 82 may be larger depending on available space.
In the same manner, it is obvious that the blower duct 92 of the
high-speed air passage 90 may have a larger cross-section.
[0054] The blower port 83 formed in the distal portion of the
low-speed air passage 80 may include deflection to further finely
adjust the amount and speed of the air current directed to a region
subject to cooling. In the same manner, the nozzle 94 in the
high-speed air passage 90 may also include such a mechanism.
[0055] The present examples and embodiments are to be considered as
illustrative and not restrictive, and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalence of the appended claims.
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